shortcut to manually Reload file from Disk

You can use the Shortcut Mapper under the Settings menu to assign a shortcut for this.

1. Go to Settings>Shortcut mapper.
2. Select the first tab (main menu).
3. Find the "reload from disk" option.
4. Put an unused shortcut.

While above answers are not wrong, It is already built-in : AltF then L

Or "File >> Reload from Disk".